Can nanotechnology help make a better COVID-19 test?

Did you know that scientists have used nanotechnology to develop a test for the  MERS coronavirus ? The results of the test can be seen by the naked eye within 10 minutes of interacting with the viral DNA, which can shorten the analysis and interpretation time. 1 Current testing for the COVID-19 virus takes hours or days. 2 So, if new, faster tests could be developed (and made widely available), it could facilitate much more efficient testing and tracking of infections. So how does this fast virus test work?

3D medical animation showing the structure of a coronavirus (image by )

First, what are coronaviruses?

If you remember from our  second episode  of the Sustainable Nano podcast, Dr. MG Finn talked about how viruses are essentially entities that exist to replicate genomic information, and the vast majority of them don’t make you sick. Viruses contain DNA or RNA (two similar, but distinct kinds of genetic material that carry the identity of the virus), which they insert into host cells to hijack the cellular machinery. This means instead of doing its regular job, the cell is put to work making more virus. In some cases, like with coronaviruses, this will make your cells get sick or die.

How coronavirus hijacks your cells (image by Stephanie Mitchell, made in ©BioRender- ) COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is a member of Coronaviridae virus family. These viruses have characteristic spikes on their protective outer layer that look like the projections from a crown. This type of virus causes respiratory and intestinal infections in animals and humans, and they were not considered especially harmful to humans until the outbreak of Severe Acute Respiratory Syndrome (SARS-CoV) in 2002-2003 and MERS-CoV in 2012. 3

Scanning Electron Microscope (SEM) images of of MERS-CoV viruses and a nice spiky crown (left by Cynthia Goldsmith/Maureen Metcalfe/Azaibi Tamin courtesy of CDC, middle from , right by Cynthia Goldsmith/Azaibi Tamin courtesy of CDC) How do we test for coronaviruses?

Just how small are coronaviruses? They are about 120 nm in diameter, which is way too small to see even with a regular microscope. It’s about 25 times smaller than an  E. coli  bacterium (~2.5 µm long), which is about 25 times smaller than the diameter of average human hair (~62.5 µm wide). Many of the gold nanoparticles we use in CSN research are about the same size as the virus, around 100 nm.

Scale of nanoparticles and viruses (~120 nm wide) compared to bacteria (~2.5 µm long) and human hair (~62.5 µm wide) (image by Stephanie Mitchell) So how can we test for these viruses if we can’t see them? The method of choice for diagnosing human coronaviruses is  polymerase chain reaction  (PCR). This technique allows scientists to make a bunch of copies of...